Just as Truth Social can use Mastodon's source code to spread lies and hate as long as they comply with the license, so can Mastodon use their own blog to disprove of Truth Social... as long as they enforce the license.
Their statement does not detract from their action.
I think it makes people believe they will enforce the license unevenly to satisfy their personal feelings about who is using it, as well as add an unwritten "these kinds of people are are not allowed to use our software" clause to their license.
A sensible person might wonder what justification you have for that belief. Looking at the respective histories of both groups, I think you'll find that the violators are the sort of people to engage in uneven enforcement.
Moreover, is there another Mastodon license violator who's getting away with it because of their ostensibly favourable politics? What does it mean for your supposition if there's only the one violator?
> I think it makes people believe they will enforce the license unevenly to satisfy their personal feelings about who is using it
Maybe they will. As copyright holders, they are allowed to do that (though I don't think they have copyright assignation, so there would also be lots of _other_ copyright holders who could attempt different enforcement, presumably).
Their statement does not detract from their action.